event.c

一个linux下的各种组播路由算法编程

/*****************************************************************************
***                      Author: Hussein F. Salama                         ***
***                       Date: September 9, 1994                          ***
***                            File: event.c                               ***
***   C++ classes Event, EventListEntry and TheEventlist to be used in a   ***
***   discrete event simulator for computer networks                       ***  
*****************************************************************************/

#include "event.h"

void TheEventList::deleteEvent() //removes the first event from the event list.
                                //returns the id of the removed event.        

{
   EventListEntry   *temp;

   temp = eventListHead;
   eventListHead = eventListHead->next;
   if (eventListHead == NULL) eventListTail = NULL;
   else eventListHead->prev = NULL;
   delete temp;
};

void TheEventList::addEventTop(EventListEntry *e) {
                                    /* inserts an event in the event list.  */
                                    /* searches the list from top down      */
                                    /* keeps the list in increasing time    */
                                    /* order, so the first event is always  */
                                    /* the most imminent one.               */
                                    /* the insert is currently done with a  */
                                    /* linear search. if time is a problem, */
                                    /* we can use a faster search.          */ 

   short stop = 0;
   EventListEntry *dum;

   e->next = eventListHead;
   if (eventListHead == NULL)
      eventListHead = eventListTail = e;
   else if (eventListHead->event->time > e->event->time) {
      eventListHead->prev = e;
      eventListHead = e;
   }
   else while(!stop) {
      dum = e->next;
      e->next = e->next->next;
      if (e->next == NULL) {
         eventListTail->next = e;
         e->prev = eventListTail;
         eventListTail = e;
         stop = 1;
      }      
      else if (e->next->event->time > e->event->time) {
         dum->next = e;
         e->prev = dum;
         e->next->prev = e;
         stop = 1;
      };
   };
};

void TheEventList::addEventBottom(EventListEntry *e) {
                                    /* inserts an event in the event list.  */
                                    /* searches the list from bottom up     */
                                    /* keeps the list in increasing time    */
                                    /* order, so the first event is always  */
                                    /* the most imminent one.               */
                                    /* the insert is currently done with a  */
                                    /* linear search. if time is a problem, */
                                    /* we can use a faster search.          */ 

   short stop = 0;
   EventListEntry *dum;

   e->prev = eventListTail;
   if (eventListTail == NULL)
      eventListHead = eventListTail = e;
   else if (eventListTail->event->time <= e->event->time) {
      eventListTail->next = e;
      eventListTail = e;
   }
   else while(!stop) {
      dum = e->prev;
      e->prev = e->prev->prev;
      if (e->prev == NULL) {
         eventListHead->prev = e;
         e->next = eventListHead;
         eventListHead = e;
         stop = 1;
      }      
      else if (e->prev->event->time <= e->event->time) {
         dum->prev = e;
         e->next = dum;
         e->prev->next = e;
         stop = 1;
      };
   };
};

void TheEventList::insertEvent(int mode, void *ptr, int n, double t, Data *d) 
                                    
/* inserts an event in the event list.                                   */
/* n is an integer; it denotes the type of the event                     *
 * that occured. t is the time instant at which the event will occur.    */
/* ptr points to the owner of the event, and d point to the event's data */
{
   EventListEntry   *tmp;

   tmp = new EventListEntry;
   tmp->event->type = n;
   tmp->event->data =d;
   tmp->event->time = t;
   //printf("insert event at time %e of type %d\n", tmp->event->time,
   //                                               tmp->event->type);
   tmp->event->pointer = ptr;
   if (mode == top) addEventTop(tmp);
   else addEventBottom(tmp);
};

void TheEventList::clear() { //Deletes all events in the list

   while (eventListHead != NULL) deleteEvent();            
};